Here are two variants of thumb nuts, one chunky and one slim.

These are made primarily for M6 nuts which have 10mm hex sizes, however due to the magic of simple mathematics you can easily scale these for use with other nuts and bolts!

Cheat sheet: M2 - 40% M3 - 55% M4 - 70% M5 - 80% M6 - 100% M7 - 110% M8 - 130% M10 - 160%